article: If you see a group of people dancing and singing on the street or in the railway station, you don't need to feel surprised. They are flash mobbers  . Who are they? Are they mobs ? Don't feel afraid hearing their name. In fact, like a mob, they are a large group of people, but they have a good purpose. They usually get together in a place, do some simple actions, and then quickly disappear.
  Flash mob is now becoming more and more popular. People use it to do many things. For example, in 2009, Michael Jackson's fans took part in a flash mob to remember him. Hundreds of his fans organized through Internet and got together outside the railway station in Liverpool. They were singing and dancing Michael's famous song "Beat It" together. And in another example, some people took part in a flash mob to tell more people not to use negative words  .
  Flash mobs give different people a chance to come together to create a good memory.
question: Where may you see a flash mob?
options: In schools. In villages. In the railway stations. On the playground.